Sound-recording process



A. J. CAWLEY.

SOUND RECORDING PROCESS. APPLICATION FILED 05c. 13. 1919.

1,426, 304 Patented June 20, 1922'.

2 SHEETS-SHEET 1.

IN V EN TOR.

A. J. 'CAWLEY.

souwn RECORDING PROCESS. 7 APPLICATION FILED DEC. I3, 1919- PatentedJune 20, 1922.

2 SHEETS-SHEET 2- HUGE INVEN TOR.

UNITED ATES;

rArE'ur mace.

ALOYSIUS J CAWLEY, OF PITTSTON, PENNSYLVANIA.

SOUND-RECORDING PROCESS.

Specification of Letters Patent.

Patented June 20, 1922.

Application filed December 13, 1919. Serial No. 344,708.

To all whom it may concern:

Be it known that I, ALoYsIUs J. CAWLEY,

a citizenof the United States, and a resident I moving picture film asit passes through the camera, thus rendering it possible to recordmotion and sound. including articulate speech, simultaneously on thesame medium.

By this process, the film is for all intents and purposes a wax-likesubstance only during the actual time of recording,

and only at the precise place on the film where the sound is to berecorded. Just as soon as the record is impressed in the medium, thelatter immediately becomes hard and tough, precluding any possibility ofdamage to it. A master record can thus be produced directly on themargin of a motion picture film, from which a metallic or other matrixmay be made.

The invention possesses several advantages over photographic methods ofsound recording. \Vith such methods it is not possible to obtain theexact form of groove desired, on account of its having been produced bychemical or similar means. Vith the herein described method, any type ofgroove, whether V-shape or other, may be impressed moreover the groovemay have the exact di-' mensions desired. It is to be further noted thatany type of sound recording, such as lateral or vertical cut, or acombination of both. may be used with this process. As the matrix ismade from the master record directly by means of a simple mechanical op-'eration, the process reduces the art of producing combined sound andpicture records on the same medium to the fewest possible manipulations.

Although the invention is especially well adapted for use in producingcombined picture andsound records on the same film, it is not at alllimited to this field, but may be used for ordinary sound recording, ashereinafter described.

Reference is to be had to the accompanying drawing forming a part of thespecification, in which like characters of reference denotecorresponding parts in all the views, and in which,

Figure 1 is a view of the heating device in contact with a celluloidfilm, together with the sound recorder.

Figure 2 is an elevation view of a plurality of such devices, eachindependently heated.

Figure 3 is an elevation view' of a heating device combined with anauxiliary temperature controller.

Figure 4 is. a sectional view of three different types of heatingdevice.

Figureo is a sectional view of a heating device in contactwith thewheel.

Figure 5 is a plan view of the heating strip in contact -with the marginof the film.

Figure 5 is a plan view of a modified form of the heating strip.

Figure 6 is an elevation view of liquid heating device.

Figure 7 is an elevation view of a device intended to remove the filmfrom contact with heat strip.

Figure 7 is a side elevation view of the same device.

It is a well known fact that celluloid, when heated to acertaintemperature, becomes plastic. If, therefore, a celluloid orsimilar film is raised to the proper temperature, and a recording stylusplaced in contact with it, sound may be recorded as readily upon it'as.upon wax. The entire film cannot be heated while passing through thecamera mechanism, because it would become distorted and rendered unfitfor further use. The invention avoids this difficulty by heating asection of the film that is substantially of only a slightly greaterwidth than that occupied by thesinuous sound groove.

Figure 1 shows a simple device which aocomplishes this, and which may beattached to any motion picture camera. The film A passes from themagazine 30 to the right and passes around the sprocket wheel 12. Theloop adjacent to the film gate 15 is shown at 13. In contact,.with thefilm is the metal strip 1, which may be of copper; this is traversed byan electric current for the purpose of elevating its temperature. Thisstrip is supported by the body 3, preferably of wood or othernonconducting material. One extremity of this strip is attached to thelever 16, which is pivoted at 17, and presses against the contact point5. When the metal film on its sprocket strip 1 becomes heated above. thedesired temperature, it is readily seen that the contact at 5 will bebroken, due to the expansion of the strip. The film A can be close to,or-in actual contact with the heating strip 1, as desired. It is obviousthat the celluloid adjacent to this strip will be rendered plasticthereby. It will, therefore, form a very sensitive sound recordingmedium for the stylus 8, which is located close to the end of the heatstrip. Just as soon as the record is impressed, the film passes awayfrom the heater and down over the sprocket wheel 12. Cooling, andconsequent hardening of the film immediately sets in. However, as thesoftened portion is enclosed on either side by a hard, tough film ofcold celluloid, there is no considerable danger to the sound record. Ifthe recording stylus is placed at a point where the film is moving atuniform speed and in advance of the loop, since this latter is vibratingrapidly, advantage can be taken of its cooling or fanning action. In theappended claims, therefore, the loop is referred to as a vibrator. Asthe device as a whole resembles a thermostat, adjustment of contactssimilar to that shown at 5, renders it possible to keep the heat stripat any desired temperature. There is, therefore, no danger ofoverheating or igniting the film. The heating circuit is showndiagrammatically, 4 being a source of power, such as a dynamo, drybattery, storage battery, etc.

A switch is shown at 6, which may send the current either through theheating circuit, or through the meter 7 in order to ascertain the amountof energy in the circuit, etc. The sound recorder is shown at 9; it ispreferably a combined microphone and sound recorder.

It is obvious that the heater may be at a temperature considerably inexcess of the desired temperature of the film. Since the latter ismoving at a fair speed, unless a comparatively great length of heatingsurface is provided, the film will not attain the same temperature asthe heat strip duringsuch comparatively short period of contact. Tngeneral, the hotter you make the heat strip, the shorter it may be.However, there is a possibility that in practice, the film may not beheated to its actual plastic temperature, as it may-be found that thesound can be recorded satisfactorily at a lower temperature. V

The heater may be of any desired length; it may also be of a formdesigned to insure contact with the film as it turns back and forth inthe camera- Furthermore, the heating ma be accomplished by means ofseveral in ependently operated electricai heaters.- This is illustratedin Figure 2, where the film A passes from the magazine over the sprocketwheel at the right and comes in contact with the U-shaped heater, anddownwards over the sprocket heel 12, through loop 13, to the film gate15. The wheel 14, which may be provided with sprocket teeth andconnected by suitable gearing such as shaft 33 and gears 31, 31". 32 and32, supported by bearings 3i and 34. to the driving mechanism of thecamera, assists in moving the film over the curved surface. There aretwo heating units (35 and. (36 connected in parallel as shown, so thatlack of uniformity in heating is minimized. The heat controlling membersare-somewhat different from those shown in Figure l; a new member 2,such as an ebonite strip, having a coefficientof expansion greater thanthe metal strip 1, is introduced. This renders the device more sensitiveto heat fluctuations. The heat controlling device shown at the right,which is similar to that described in Figure 3, is constructed of twomembers, 1 and 2, which may be made of metal and ebonite respectivelyand rigidly attached; the coefiicient of expansion of ebonite is muchgreater than that of the metal. T pon heating the combined strips, theybend away from the contact point and thus shut off the electric current.

Figure 3 shows a heating device connected with an auxiliary safetydevice. which may be a fuse or any kind of thermostat, for instance of'the fluid column type. A fuseis illustrated in the figure. Tn thecompartment 10, it is shown at 11. The recorder 9 shown in this figureand also in Figure 2, is provided with a bell crank so that the plane ofthe diaphragm is parallel to the film surface. 3

Tu Figure 4: three cross-sectional views-are shown. illustratingdifferent arrangements of the heat strips. The central view shows thatthe heat strip may be much narrower than the body of the heater proper.The third view illustrates the fact that the heat strip may be heldclose to, but not in actual contact with the film.

The recording stylus passes through the heater body by means of agroove, which must be of a width substantially greater than the greatestamplitude of vibration of the stylus. Figure 5 shows the stylus 8 in itsgrooye, which is formed in the supporting body 3 and heat strip 1. Thefilm margin is shown at A resting upon the sprocket wheel 12. Figure 5showsthe device with everything removed but the heat strip 1, whichrests upon the margin of the film A. The stylus point 8 impresses therecord groove 21. Figure 5 illustrates a modification of the heat strip1, whereby all possible danger of imparting any heat to the film afterthe record has been impressed upon it, is avoided. To accomplish this,the strip is bent to one side as shown.

If it is desired to take a-f'urther precaution against overheating thefilm, a fiuid heater may be used. Figure 6 shows an oblong metalcontainer 28, preferably of wedge-like cross section. having itsnarrowest surface in contact with the film A. This container is filledwith water, an aqueous solution. or a fluid having a higher boilingpoint than either of those, as desired. Electrical heaters 27, suchascoils of wire, are located in this liquid, and maintain it at itsboiling point. heated by passing a suitable'current directly through it,if it is ionizable. The vapors pass through the tube 29, which acts toa" certain extent as a reflux air condenser, bringing most of them tothe liquid condition again. If desired, the tube may be arranged in theform of an air cooled coil 35, which will still further reduce the lossby evaporation. The stylus 8 is shown at the left of the heater.

Figure 7 is a transverse view and Figure b is a side view of a devicedesigned for the purpose of lifting the film away from the heater. Thisis: desirable. for instance when the film is stopped and it is notdesirable to turn off the electric .current. Any possible damage causedby leaving the film in contact with the heat strip for an excessiveperiod is thus avoided, particularly if the heat strip is at atemperature greater than the plastic temperature of the celluloid. Itconsists of a metal frame 23, passing through guides 24 and supportingthe rolls 22. A number of springs, one of which is shown at 18,supported by the shelf-like extension of the frame, hold the filmnormally in contact with the heat strip. Any kind of cushions, pneumatic37, fibrous 38 or other, may be substituted for the springs. The frameis moved downward by means of the crank arm 26, which is connected bymeans of a-shaft 39 to an operating lever -10 or similar device locatedon the outside of the camera.

In the actual operation of the apparatus, it is only necessary to turnon the heater by closing the electrical circuit by means of switch 6',while focusing, and when the desired temperature is reached, the film.is moved, when the sound record will be impressed in the softenedcelluloid.

An absolutely uniform speed is necessary for sound recording, and forthis reason the camera should be driven by some form of motor. A smallgenerator 47 may be operated by the motor in order to furnish theheating current. However, inexpensive, small dry batteries may be usedfor this purpose.

. As the heatstrip is surrounded by heat insulators 3, there is aconsiderable saving of current. it is not necessarily made of metal, assome other material such as ebonite may be used. Moreover, as the heatedsection or that part of the film in which the record. 8 is impressed, islocated between The liquid could also bethe edge of the film and the rowof sprocket holes. no damage can be done to the film, there being nostrain tending to stretch or shear it along this section. Instead, thesprocket wheels, such as 12 etc., rather tend to hold it together as itpasses around them. Further, it is desirable to have the heated sectionslightly nearer to the edge of the film than to the row of sprocketholes.

If a liquid heating device is used. it should be provided with atransparent section 41. in order .to ascertain the amount of liquidpresent. Any liquid of constant boiling point may be used, a fixedtemperature being thus assured.

The meter 4 shown in the electric heating circuit is preferably a smallcombined ammeter and voltmeter as is ordinarily used with dry batteries.

The exact location of the recording of the sound is not limited to anyparticular place on the film; it may be recorded before or after thepoint of exposure of the picture, but should be at a point where thefilm is running with a uniform speed.

The result of the process is a negative motion picture film having itsappropriate .master record located in the film body, preferably on amargin or margins. A matrix can be made from this.

Where rolls are mentioned in the specification, it is to be definitelyunderstood that any means of impressing heat and pressure is designated.

The invention is not limited to the recording of sound, or thecontacting of the stylus on the celluloid side of the film. as it may berecorded on the gelatine side, if desired. The gelatine, being flexible,may be displaced downwards into the celluloid body.

The term heater embraces the compactly arranged heater as a wholecomposed of the elements 1, 3 etc., including the temperature regulator,such as 5, 16. By heat strip is implied the strip or strips 1, 2,concerned with the direct heating of thefilm. It is to be definitelyunderstood that the invention is not limited to any particular type oftemperature regulator. That shown being rather a general representationthan a specific type.

By adjusting the contact points 5, a definite temperature may be securedwith great nicety. It will thus be found that by adjusting the contacts,a certain degree of softness of the film A. will be secured at which themost satisfactory sound recording may be accomplished. This, however,may not be the temperature at which the medium finds its greatestplasticity. The invention is therefore, not limited to the attainment,or maintenance of any particular temperature.

One can readily see that the three main elements of the combination,heater, recorder and recording medium, constituting the re means of heatwhich is below the ignition or fusion point of said film, vibrating astylus in contact with said portion, independently feeding sections ofthe film to form an intermediate, oscillating loop and accelerating thehardening of said portion by the rapid movement of the loop.

2. A process of sound recording, which consists in applying anon-igniting, nonfusing, plasticizing degree of heat to a portion of thewidth of a film, preferably on its margin, to soften same, and vibratinga stylus in contact with said softened portion.

3. A process of sound recording. which consists in independently feedingsections of film to form a transversely moving loop. softening byapplication of heat a portion of the width of a film immediately beforesaid film enters the loop, "vibrating a stylus in contact with saidportion, and then passing same through the loop to harden said film.

4. A process of sound recording which consists in applying heat to aportion of the width of a film on and intheimmediate vicinity of theproposed sound groove. and impressing said groove by vibrating a stylusin contact with said portion.

5. A process of sound recording. which consists in placing a heat stripin contact with a film to render it plastic along the line of contact.and subsequently vibrating a stylus along the plastic portion.

6. A sound recording device, consisting of a long, narrow heateradjacent to a portion of the width of a film, preferably on its margin,and a recording stylus acting to impress a groove in said portion.

7. A sound recording device. consisting of an electrical heater andmeans to prevent attainment of fusion and ignition, which heater closelyapproaches a moving film or surface, and a recording stylus whichimpresses a groove in said film.

8. A sound recording device, consisting of a heater provided withauxiliary means for maintaining constant temperature adjacent to aportion of the width of a recording element to soften same, a soundrecording stylus vibrating in contact with said portion, and a vibratorto accelerate hardening by rapid vibration of said recording element inthe air.

9. A sound recording device, consisting of a film. a heater whichsoftens a portion of the width of said film. a sound recorder whosevibrating stylus is in contact with said portion passing beneath saidheater: said styl is-im'pressing a groove in said film. and .a filmvibrator to accelerate hardening by rapid vibration of said film in theair.

10. A sound recording device. consisting of a heater provided with heatinsulators adjacent to a portion of the width of a moving film, atemperature controller. a vibrating stylus so placed as to contact withsaid portion before it cools, and a film vibrator to acceleratehardening by rapid vibration of said film in the air.

11. A sound recording device. consisting of a heater provided with heatinsulators adjacent to a portion of the width of a film to soften same,a vibrating stylus in contact with said softened portion. and a filmvibrator to accelerate hardening by rapid vibration of said film in theair.

12. A. sound recording device. consisting of a. heater provided withheat insulators and a temperature controller acting to soften a portionof the width of a film. and a stylus vibrating in contact with saidportion to impress a sound groove therein.

ALOYSIUS J. C AWLE Y.

